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<head><meta charset="utf-8"><title>pgo on ci · t-infra · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/242791-t-infra/index.html">t-infra</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/242791-t-infra/topic/pgo.20on.20ci.html">pgo on ci</a></h3>

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<a name="220582526"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/242791-t-infra/topic/pgo%20on%20ci/near/220582526" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/242791-t-infra/topic/pgo.20on.20ci.html#220582526">(Dec 21 2020 at 13:21)</a>:</h4>
<p>FYI, I am proposing a 15 minute increase for the linux CI builder in <a href="https://github.com/rust-lang/rust/pull/80262">https://github.com/rust-lang/rust/pull/80262</a>, which yields good performance benefits to end users (5-20% wall time benefits)</p>



<a name="220582551"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/242791-t-infra/topic/pgo%20on%20ci/near/220582551" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/242791-t-infra/topic/pgo.20on.20ci.html#220582551">(Dec 21 2020 at 13:21)</a>:</h4>
<p>that makes that builder be roughly one hour long, which is still quite fast</p>



<a name="220601895"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/242791-t-infra/topic/pgo%20on%20ci/near/220601895" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> cuviper <a href="https://rust-lang.github.io/zulip_archive/stream/242791-t-infra/topic/pgo.20on.20ci.html#220601895">(Dec 21 2020 at 16:26)</a>:</h4>
<p>And by "the linux CI builder", you specifically mean only <code>dist-x86_64-linux</code> (gnu), not any other Linux targets</p>



<a name="220601974"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/242791-t-infra/topic/pgo%20on%20ci/near/220601974" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> cuviper <a href="https://rust-lang.github.io/zulip_archive/stream/242791-t-infra/topic/pgo.20on.20ci.html#220601974">(Dec 21 2020 at 16:28)</a>:</h4>
<p>PGO requires execution, so it can only work for native host CI builds, but that could include i686 or aarch64</p>



<a name="220602520"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/242791-t-infra/topic/pgo%20on%20ci/near/220602520" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/242791-t-infra/topic/pgo.20on.20ci.html#220602520">(Dec 21 2020 at 16:33)</a>:</h4>
<p>yes just that builder</p>



<a name="220602643"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/242791-t-infra/topic/pgo%20on%20ci/near/220602643" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/242791-t-infra/topic/pgo.20on.20ci.html#220602643">(Dec 21 2020 at 16:34)</a>:</h4>
<p>I think it may be possible for us to use the profile from that builder on other targets (when cross compiling) but that will need more investigation and people with access to hardware with native support so we can benchmark whether that PGO works. For rustc I expect there to not be significant differences in generated code so it might work, not sure</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/242791-t-infra/topic/pgo%20on%20ci/near/220677219" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/242791-t-infra/topic/pgo.20on.20ci.html#220677219">(Dec 22 2020 at 10:40)</a>:</h4>
<p>5-20% of wall time improvement sounds excellent!</p>



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<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/242791-t-infra/topic/pgo%20on%20ci/near/220677255" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/242791-t-infra/topic/pgo.20on.20ci.html#220677255">(Dec 22 2020 at 10:40)</a>:</h4>
<p>I see no problem in increasing that runtime, especially since other builders are way slower</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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